The invention relates to a PAL comb filter, for use in an apparatus for playing back video signals recorded in adjacent tracks on a record carrier for chroma cross-talk reduction by means of chroma carrier phase inversion, comprising a first and a second transmission path, input means for applying a PAL chroma signal to the two transmission paths, a delay network for delaying the PAL chroma signal in the first path relative to the PAL chroma signal in the other path, and a signal combination circuit for combining the PAL chroma signal in the second path and the PAL chroma signal delayed in the first path with the correct polarity relative to each other in such a way that the result of this combination is again a
chroma signal. In this respect a PAL chroma signal is to be understood to mean a chroma signal in which the phase of one of two quadrature-modulated color components changes every alternate line. Consequently, the term "PAL chroma signal" is not limited to inter alia the standard television carrier frequency of 4.433 MHz.
Such a comb filter is used for filtering PAL chroma signals in, for example, video cassette recorders and video disk systems. In particular, in recording and playback systems in which video signals are or have been recorded in parallel tracks, such a PAL comb filter is used for suppressing chroma crosstalk from adjacent tracks. A disadvantage of the known PAL comb filters is that they require the use of a delay network with a time delay equal to the duration of two lines of the video picture, which inter alia gives rise to a vertical shift of the color picture relative to the luminance picture and a degradation of the resolution in the vertical direction, which effects are particularly annoying in video recording, when magnetic copying video tapes. A solution to this problem is to convert the PAL chroma signal into a quasi-NTSC chroma signal and, after filtration, reconvert it, so that it suffices to use a delay network having a time delay equal to one line period of the video picture. The disadvantage of this is that the video signal must be switched over every alternate line, which gives rise to phase errors in the resulting PAL chroma signal with consequent color errors. A further disadvantage is that owing to this quasi PAL-NTSC conversion, the advantages of PAL coding are lost in that part of the video system where the quasi-NTSC signal is processed.